Late 2376.  Starship Voyager transmits data from the Delta Quadrant regarding development of "quantum slipstream drive", a form of transwarp far beyond velocity limits of standard warp drive.  Although Voyager's attempt to travel via slipstream fails, Starfleet sees the potential of QSD and secretly commissions Starfleet R & D to develop their own working version, incorporating the Voyager data.

At the Utopia Planitia Fleet Yards facility, construction is accelerated on U.S.S. Arcadia, an Intrepid-class vessel incorporating design advancements at the time--one more ship to replace many lost in the Dominion War.  Starfleet R & D, in conjunction with the Advanced Starship Design Bureau, requisitions and receives Arcadia as a testbed for the QSD effort.  Due to the potentially sensitive tactical nature of slipstream drive, the project is termed "Purple Dog" to throw off enemy infiltrators.

Early 2377.  The QSD project is hampered by lack of a sufficient power-source for quantum drive, as well as manual inability to compensate for phase-variances.  Numerous simulations end in disaster.  This also interfered with the Voyager's slipstream run.

Mid-2377.  ASDB experts arrive at a means to solve the phase-variance problem by creating a spacial integral deflector array which adjusts individually to variances throughout the curvature of the slipstream's leading edge.  Also key to this portion of the dilemma is the development of a compression power system which can, in simulation, maintain slipstream without adverse navigational or structural aberrances.

However, efforts to synthesize benamite, a crystal form of which powered Voyager's quantum drive, meet with failure.  This problem is solved with the creation of artificial wormholes, based on research by Trill scientist Lenara Kahn.  A wormhole is opened to the Delta Quadrant in the hopes of giving Voyager access to the Alpha Quadrant, but Voyager has moved out of range.  The U.S.S. Antietam enters the Delta Quadrant for an exploratory run; among its mission objectives: the procurement of benamite.  A month later, Antietam returns to the Alpha Quadrant with the coveted substance.  The benamite is dispatched to Utopia Planitia for immediate testing aboard the Arcadia.

Late 2377.  After months of standard and rigorous testing for both warp and slipstream capabilities, the final design of the Quantum Slipstream Drive is submitted and approved.  This requires an overhaul and refit of the Arcadia's hull to meet pressure-gradient and structural integrity requirements, which takes several more months to complete.

Early 2378.  The completion of Project: Purple Dog stumbles when Federation media get wind of the QSD project and nearly upset security surrounding the Arcadia.  The ship is moved from Utopia Planitia to a remote orbital facility near Pluto to undergo final testing.

Mid-2378.  Repeated QSD test runs across Sector 001 and surrounding regions pass the grade, and plans are made for a full-scale run across the Federation.  Due to her experimental nature and the classified status of QSD, the ship is given the registry of NX-A1.  She is the first Federation vessel to sport the "U.F.S." prefix (United Federation Starship), reflecting the united aim of the Federation's future interests.  Captain Stephen April is assigned to command; the first crew-members are placed onboard.

Late 2378.  The intrusion of a Kelvan "bioship" from beyond the galaxy compels Starfleet Command to launch Arcadia ahead of schedule.  The ship flies at standard warp from Earth to Vulcan to pick up final crew assignments, and from there proceeds on its maiden voyage, to (successfully) halt the Kelvan invasion.

In the far reaches of the Alpha Quadrant, Arcadia visits the planet Grazellius; establishes diplomatic relations.

Ferengi opportunists attempt to procure Arcadia's quantum slipstream drive.

Late 2379-early 2380.  After proving herself in several missions, Arcadia receives an extensive, three-month-long overhaul and redesign, becoming the new "Quantum-class" prototype.  The ship's registry is changed to NCC-A1 and Arcadia is officially commissioned for the first time.

2380.  Arcadia becomes the Federation's first vessel to visit galaxy M87, 50 million light-years away.

Returning from M87, Arcadia discovers another Arcadia, NX-A1, from a parallel universe, marooned on Meloc II.

2382.  Starfleet learns of the "Usurpers", a mysterious and dangerous race who threaten the Federation.  Arcadia travels into the No'Zal Cluster to halt the Usurpers' impending invasion.  A hostile encounter with Romulan ships manipulated by the Usurpers leaves Captain April crippled.  The mission succeeds, however, and the Usurpers are contained.

Captain Stephen April retires.  Neria April, his daughter from an alternate future, is appointed to succeed him as captain.

Arcadia undertakes a mission into the mysterious "Nexus", emerging in an alternate future where a "jihad" (holy war) has split the Federation.  Upon returning to her own time, this conflict is prevented from occurring.  Starfleet decommissions and sequesters the ship for study by the Federation's Department of Temporal Affairs.  Arcadia's crew is reassigned and knowledge of the alternate future is classified.

2385.  After a three-year hiatus, Arcadia is cleared to resume active service.  Most of her previous crew, including Captain Stephen April, returns for the ship's relaunch.

The Arcadia journeys to the Occlua Sector, a temporally unstable region of space home to mysterious creatures called "Bees", to stop a rogue ship from unleashing temporal havoc.

Late 2385.  On a mission to the Delta Quadrant, investigating strange behavior of comets in the Wenga system, Arcadia makes first contact with the Hledexh, a new Delta Quadrant race.

The crew takes an extended leave while the ship is refitted at Starbase 514, providing new holographic control interfaces and systems upgrades.

Starfleet docks the ship in response to an outbreak of a possibly contagious disease.